RESPIRATION IN AIR 



67 



ures accurately the amount of work, a linear relationship as 

 shown in Fig. 39 is found between the rate of work and the 

 metabolism as measured by the oxygen uptake. One set of 

 results, marked •, were obtained on an ordinary bicycle 

 ergometer on which the subject must keep himself fixed by 



360 



720 



mo 



IW0 



Fig. 39. Relation between oxygen absorption in liters per minute and rate of 

 work in kgm per min. in a human subject. (M. Nielsen.) 



gripping the handle bars, while the others were obtained with 

 the subject working the ergometer in a reclining position in an 

 easy chair. In spite of this difference the results are identical. 

 The maximum 2 uptake in a trained athlete is between 4 

 and 5 1/min. From determinations of the diffusion of carbon 

 monoxide from the alveolar air into the blood of human sub- 

 jects, Bpje (1936) calculates a maximum 2 uptake of 4.5 

 1/min. Special experiments (M. Nielsen and O. Hansen, 

 1937) with breathing of oxygen-enriched air show, however, 

 that the diffusion rate of oxygen into the blood is not the 

 limiting factor for the O2 absorption. There is reason to 

 suspect that the results of diffusion determinations are sys- 

 tematically too low (Hartridge and Roughton, 1927). 



